The present invention relates to a mould for the continuous casting of metal.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
Moulds of copper or copper alloys for the continuous casting of sections of steel or other metals having a high melting point have been described many times in the related art. Ideally, a cast strand produced by continuously casting steel should have the shape of the mould from which it was cast, it being slightly smaller than the mould due to the contraction of the metal being cast. On occasion this shape is lost and this often results in cracks and tears in the solid section. This problem becomes worse when casting steel having a carbon content between 0.2 and 0.4 mass percentage. In this carbon content range there is a marked tendency for a square or rectangular configuration to become rhomboid. It has been shown that as the rhomboidal configuration of the cast strand increases and the rectangularity decreases, the extent of the internal tearing is so great that it leads to a deterioration in quality of the cast strand and in an extreme case renders its disposal as scrap material necessary. This problem becomes increasingly relevant when using high-speed continuous casting facilities.
Various approaches have been proposed to address this problem, such as: changing the geometry of the mould cavity to be closer to the contraction rate of the metal being cast, changing cooling of the mould strand, or changing the steel composition. Although a change in the chemical composition of steel alloy for high-speed continuous casting may appear to be sound, the downside is the increase in costs for the steel. Therefore, the approach normally taken heretofore is directed towards a modification of the mould cavity so that the cast strand can be solidified as evenly as possible. The shell growth of the cast strand, i.e. the solidification from outside to inside should occur as evenly as possible because uneven solidification of the cast strand is the cause for the rhombic configuration of the ideally rectangular cast strand. Fairly complicated geometric mould cavities have been proposed; rendering the overall production, however, more complex and incurring increased maintenance costs when the mould has to be refinished because of wear. (US 2007/0125511 A1).
It would therefore be desirable and advantageous to provide an improved mould for the continuous casting of metal to obviate prior art shortcomings and to enable realization of a cast strand with superior shape accuracy without the need to change the composition of the metal alloy of the cast strand.